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prodigal sun

forget what you used to know about photovoltaics.

SunPower Corp.Despite lagging behind European photovoltaic installations such as this one in Switzerland, U.S. solarelectric generation is growing at a steady clip due to falling panel prices and rising fossil fuel costs.

Architects David Arkin, AIA, and Anni Tilt installed a solar system on their northern California home eight years ago, and judging from the results they've seen, there's little doubt they would do it again. “In our home we use roughly 4.5 to 6 kilowatt-hours per day,” says Arkin, principal of Arkin Tilt Architects in Berkeley, Calif. “The [state] average is around 21.”

Arkin says he and Tilt cool their house passively, using gas for cooking and heating and to power the backup hot-water tank. During off-peak hours, the home's solar panels generate an energy surplus that goes back into the power grid—and results in an average monthly electricity bill of $6. “There are few thrills in this world greater than watching your meter spin backward,” he says.

hot and cold
Harnessing energy from the sun is an old idea whose time may finally be dawning. With varying degrees of success, today's architects are using the sun for passive heating and hot water or photovoltaic (PV) solar panels to convert sunlight into electricity. Panels come in two forms: amorphous or crystalline (mono or poly). “Amorphous panels are the VW Beetle of the industry,” says Lawrence Scarpa, AIA, principal, Pugh + Scarpa, Santa Monica, Calif. “They are cheaper to make and less temperamental, but they are also less efficient. Polycrystalline, on the other hand, is more high-performance and more efficient, but [it's also] very temperamental and easily damaged.”

Although it's clean and renewable, solar technology also can be inefficient and costly. According to Warrenton, Va., architect Angus Macdonald, AIA, “a comprehensive solar system to supply electricity, hot water, and heating for a three-bedroom, 2,500-square-foot home costs about $30,000 if it is to be grid independent for a ... time.” Even so, Macdonald says solar power is increasing in popularity due to rising fossil fuel prices—a trend he expects to continue as fuel costs go even higher.

Solar power proponents point to Germany and Japan by way of example. High fuel prices forced those countries to invest in solar energy, and business is booming. According to Solarbuzz, a San Francisco-based solar research and consulting company, PV installations in Germany jumped 152 percent in 2004.

Other countries are seeing similar spikes. In the United States, for instance, the number of PV installations rose 27 percent in 2004. (Ironically, the share of electricity produced by solar sources in this country hovers below 1 percent.)

According to architect Ken Wilson, AIA, principal, Envision Design, Washington, D.C., a confluence of factors might make solar technology a competitive energy alternative sooner than some might think. “I hear that the cost is coming down, panels are getting more efficient, and tax incentives are helping to increase interest,” he says.

Others confirm that at least one barrier to entry is cracking. Solar technology in the 1970s and ‘80s “was 10 times more expensive than it is today,” says Rhone Resch, executive director of the Washington, D.C.-based Solar Energy Industries Association. Given the “90 percent reduction in price” that has occurred, he adds, a system can pay for itself in 10 years or less.

That price drop certainly has piqued the interest of volume builders, who are more sensitive to the bottom line. For example, Shea Homes announced in 2000 that it was developing in San Diego a high-performance subdivision in which each home has a 1.32-kilowatt PV system and solar-generated water heating.

It's not surprising that such a project would exist in California, where residents are known for their environmental consciousness. In fact, the state is widely considered to be the primary source of solar's popularity surge. “California accounts for 85 percent of the [U.S.] PV panel market,” says Julie Blunden, vice president of external affairs for Sunnyvale, Calif.-based PV manufacturer SunPower Corp. “We also have some of the highest marginal energy rates in the country, too. As a result, a combination of rebates and incentives make solar ... a good option.”